Explanation
The minimum carbon dioxide design concentration for extinguishment of an ethylene fire is43%. This is based on the cup burner method, which is a standard test to determine the flame extinguishing concentration of a gaseous agent for a liquid fuel. Ethylene is a flammable gas that can form a liquid under pressure. The cup burner method involves placing a liquid fuel in a metal cup with a central nozzle, and flowing a gaseous agent through the nozzle to create a diffusion flame. The gaseous agent is gradually increased until the flame is extinguished.The minimum concentration of the gaseous agent required to extinguish the flame is recorded as the flame extinguishing concentration1.According to a study by NIST, the flame extinguishing concentration of carbon dioxide for ethylene was found to be 43%1.This value is also consistent with the NFPA 12 standard, which specifies the minimum design concentrations of carbon dioxide for various fuels, including ethylene2.